The overall objective of the Analytical Chemistry Core is to provide analytical support for the human monitoring, animal model, and cell biology projects in the program project. We will apply techniques to the research projects as appropriate, and will advance the technology upon which the analytical methodology is based. This core will conduct new analyses on serum samples from the CHARGE study, collected during the previous funding period, new samples from the CHARGEBACK and MARBLES study (see Projects 1 and 2). We will evaluate new methods to apply to the prospective study of future siblings and to test specific hypotheses. A major goal will be to generate data sets of xenobiotic exposure and metabolomic biomarkers to regress against transcriptome and proteome data by determining both xenobiotic exposure and levels of endogenous metabolites on selected . We will evaluate metabolite profiles in animal models emphasizing immune dysfunction. In human samples, we will pay particular attention to metabolites indicative of inflammatory status and plasma leptin levels recently found as a biomarker to distinguish between early onset and clinical regression autism. We also will monitor the metabolite profiles in T cells, B cells and natural killer (NK) cells of normal and autistic children with and without exposure to xenobiotics. Of equal importance we will provide a walk up instrument and consultation service in analytical chemistry for the entire core the Specific Aims are: 1. Establish the metabolic pathways responsible for variations in lipid composition between autistic children and their siblings and between normal and immunologically challenged animal models of autism. 2. Use global metabolomic procedures to search for biomarkers of autism. 3. Provide analytical data on pesticide and other xenobiotic levels in cell and in vivo model systems and in serum samples from the CHARGE, CHARGE-BACK, MARBLES, and other successor studies. 4. Develop new analytical methods for xenobiotics of interest to scientists in the program project.